Optimized CO2 operated air-conditioning system

Abstract

An optimized CO 2 air-conditioning system for a vehicle has individual components designed and/or matched to one another in such a way that if the high pressures in the high-pressure section deviate by up to ±30% from the optimum high pressures, the associated optimum performance figures are reduced by no more than 20%. The individual components include a controllable compressor, a gas cooler, an internal heat exchanger, an evaporator and an accumulator. As a result, a fixed throttle expansion member can be used between the high-pressure and low-pressure sections of the system.

What is claimed is:  
     
       1. An air-conditioning system operated with CO 2  refrigerant comprising: 
       a compressor having pressure output and a suction inlet;  
       a high-pressure section connected to said pressure output of said compressor and including a gas cooler and a first branch of an internal heat exchanger connected in series;  
       a low-pressure section connected to said suction inlet of said compressor and including an evaporator, an accumulator and a second branch of said internal heat exchanger connected in series;  
       an expansion member connecting said high-pressure section to said low-pressure section;  
       a predetermined quantity of CO 2  refrigerant flowing in the system; and  
       a control unit having an output connected to said compressor for controlling said pressure output of said compressor in response to an input signal at an input connected to a sensor, said sensor being at least one of a pressure sensor registering a pressure of said suction inlet and a temperature sensor registering a temperature of cooled air exhausted from said evaporator.  
     
     
       2. The air-conditioning system according to  claim 1  wherein said control unit receives a signal from a temperature sensor registering desired cooling of air flowing through said evaporator and a signal from a temperature sensor registering a temperature of ambient air. 
     
     
       3. An air-conditioning system operated with CO 2  refrigerant comprising: 
       a compressor having a pressure output and a suction inlet;  
       a high-pressure section connected to said pressure output of said compressor and including a gas cooler and a first branch of an internal heat exchanger connected in series;  
       a low-pressure section connected to said suction inlet of said compressor and including an evaporator, an accumulator and a second branch of said internal heat exchanger connected in series;  
       a plurality of fixed expansion members connected in parallel between said high-pressure section and said low-pressure section; and  
       a predetermined quantity of CO 2  refrigerant flowing in the system.  
     
     
       4. The air-conditioning system according to  claim 3  including a control unit for selectively controlling flow through at least one of said plurality of expansion members. 
     
     
       5. An air-conditioning system operated with CO 2  refrigerant comprising: 
       a compressor having a pressure output and a suction inlet;  
       a high-pressure section connected to said pressure output of said compressor and including a gas cooler and a first branch of an internal heat exchanger connected in series;  
       a low-pressure section connected to said suction inlet of said compressor and including an evaporator, an accumulator and a second branch of said internal heat exchanger connected in series;  
       a fixed expansion member connecting said high-pressure section to said low-pressure section;  
       a predetermined quantity of CO 2  refrigerant flowing in the system; and  
       a control unit having an output connected to said compressor for controlling said pressure output of said compressor in response to an input signal at an input connected to a sensor, said sensor being at least one of a pressure sensor registering a pressure of said suction inlet and a temperature sensor registering a temperature of cooled air exhausted from said evaporator.